Evaluation of s-nitrosothiol and thiol/disulfide levels in patients with acute coronary syndrome and normal coronary arteries

Background: Acute coronary syndrome (ACS) is a condition in which the coronary arteries supplying blood to the heart are infarcted with the formation of a plaque and thrombus. Oxidative stress is very important in the pathogenesis of ACS. The level of nitric oxide (NO), an antioxidant molecule, is important to protect the heart from ischemic damage in ACS patients. S-nitrosothiol (SNO) is a molecule that represent the main form of NO storage in the vascular structure. They are an evolving class of NO donors with the potential to restore NO bioavailability. In addition, dynamic thiol/disulfide homeostasis is known to play an important role in maintaining the oxidant-antioxidant balance. In this study, our aim is to evaluate the oxidative/nitrosative stress status according to SNO level and thiol/disulfide homeostasis in patients with ACS, including patients with ST-elevation myocardial infarction and non-ST-elevation myocardial infarction. Method: The study included 124 patients who were admitted to the adult emergency service of Ankara City Hospital between September to December 2021 and who were hospitalized with the diagnosis of ACS and underwent coronary angiography (CAG). As the control group, 124 consecutive individuals who applied to the cardiology outpatient clinic with cardiac complaints between these dates and underwent CAG and were found to have normal coronary arteries or non-critical coronary artery stenosis as a result of CAG were included. Blood was drawn from all participants included in the study to determine SNO, nitrite, total thiol, native thiol, and disulfide levels within 4-8 hours after CAG. In addition to routine blood tests of the patient and control groups, high-sensitivity troponin I values of the individuals in the control group were also measured. In addition, all participants underwent detailed transthoracic echocardiography by a cardiologist. Results: The mean age of the study population was 60.2 ± 11.8 years and 34.3% of them were male. The mean age of the patient group was higher than the individuals in the control group (62.9 ± 13.8 vs. 57.6 ± 8.7, successively, p< 0.001). Serum SNO v levels were found to be significantly lower in ACS patients compared to the control group (0.3 ± 0.08 vs. 0.4 ± 0.10 μmol/L, successively, p< 0.001). In addition, while the total thiol, native thiol, native thiol/total thiol levels were lower in the patient group compared to the control group, nitrite, disulfide/native thiol and disulfide/total thiol levels were higher. As a result of multivariate logistic regression analysis, it was determined that SNO, age, gender, smoking, low-density lipoprotein cholesterol and HbA1c were independent predictors in predicting ACS patients. From these 6 independent variables, a nomogram was constructed to predict a patient's probability of ACS. It was observed that the higher the total score obtained in the nomogram, the higher the probability of the patient to have ACS. In the analysis of the receiver operating characteristic (ROC) curve, which shows the performance of the final model in predicting ACS, the accuracy of all these variables in predicting ACS was determined as 85% (area under the curve 0.855; 95% CI 0.839-0.953; p< 0.001). Conclusion: As a result of this study, the reason why SNO and thiol levels were found to be significantly lower in ACS patients may be due to increased oxidative stress and excessive NO secretion secondary to inflammation. In addition, SNO molecule, which has been shown to be an independent predictor of ACS diagnosis, may be an inspiration for the development of diagnosis and treatment algorithms for ACS patients in the future. However, larger scale and randomized studies are needed for this. Keywords: Acute coronary syndrome, ST segment elevation myocardial infarction, non-ST-elevation myocardial infarction, S-nitrosothiol, thiol, disulfide, NO